1. Field of the Invention
The present invention relates to a control device with a mobile component mounted on a ball pivot, this device comprising means for detecting the position of the mobile component, connected to information processing means which generate signals representing the displacement of said component with respect to two or three axes of rotation.
2. Brief Description of the Prior Art
Various means have already been proposed for detecting displacements of a mobile component formed of a lever in such a device, however, the known means have various notable drawbacks. For example, potentiometric sensors have problems of contact wear and fouling, they are lacking in linearity and they are sensitive to the environment. Rotary sensors with optical detection of occultations do not operate satisfactorily at low or high displacement velocities of the lever and depending on circumstances, they only detect the velocity or the position of the lever, and they are expensive. Field-effect sensors are very expensive and their implementation is complex and their sensitivity to external perturbations is very large. Finally, optical sensors used in the prior art generally comprise four photodetectors or photodetectors with four quadrants or an array of photodetectors with two rows and two columns, and can only track very limited angular displacements of the lever around one axis or two axes of rotation.
The present invention essentially relates to a device of the aforementioned type, which does not have such drawbacks of known means.
Accordingly, it is a primary object of the present invention to provide an improved control device equipped with reliable and inexpensive sensors, for detecting the position of the mobile component and for tracking its displacements around three axes of rotation over angular displacements of maximum value.
For this purpose, it provides a control device with a mobile component mounted on a ball pivot, wherein said component is adapted to be rotated around at least two different axes and the device comprises detection means for optically detecting the position of said component, said detection means being connected with information processing means and comprising at least two photodetector arrays for detecting points uniformly distributed over at least a support with the shape of a sphere or portion of a sphere, the arrays and the support being positioned around the ball pivot of said component and some being fixed and others being mobile and secured to the component.
By this combination of the photodetector arrays and of the support bearing uniformly distributed points optically detectable by the photodetector arrays, the positions of the mobile component and its displacements around two or three axes of rotation may be determined over large angular displacements, typically larger than 45xc2x0 and which may attain 180xc2x0 or even 360xc2x0 around at least one aforementioned axis.
Further, the device according to the invention does not undergo any wear or hysteresis phenomenon able to interfere with the detection of the position and of the displacements of the mobile component, except as far as the ball pivot is concerned.
In a preferred embodiment of the invention, the photodetector arrays are fixed and the point support(s) are mobile and borne by the mobile component.
Preferably, the photodetector arrays are positioned at 90xc2x0 to one another around an axis of rotation of the mobile component, which may be the axis of the component itself in a particular position, for example, a rest position.
The information processing means to which are connected the photodetector arrays comprise programmed means for determining the positions of the aforementioned points with respect to the photodetector arrays and for tracking the trajectories of these points upon displacements of the mobile component.
These programmed means, for example, are adapted for first searching within each array for a group of three photodetectors, which see a same point, and then, among the remaining photodetectors, the groups of two photodetectors seeing a same point, and, among the remaining photodetectors, the photodetector(s) which each see a point or a portion of a point overlapping an edge of an array, and then for determining the positions of the centers of the points seen by the photodetectors, and for repeating these determinations with a sufficient frequency so that the displacements of the points between two successive determinations are less than the radius of these points.
This processing may be performed at high speed by a microprocessor of a commercially available type.
Generally, the invention is applicable to control handles of the xe2x80x9cjoystickxe2x80x9d type which may be used with video game consoles and computers, to measuring systems which use ball pivot mounted components, to prostheses, joints of robotic systems, and to any device with a jointed lever around two or three axes of rotation, notably gearshift levers for motor vehicles.